I sent this email to Forced Inductions
In blue I answered a few of my own questions.

Here is the set up. GM gen 3 36X cid. ETP heads, big turbo cam ect.
I looking to go 8.50's @ 3300 lb and turn about 7700 rpm.
I've always run garret based units. (turbonetics and gt based)
I have not even considered BW stuff mainly due to physical size. It all has to fit under a FD rx7 hood.
I think twin "non GT housing" Garret based units will be easier to package.

I currently have a TC76 F1 from you guys, I know you guys stay busy so I tried to make leave space in the email so you can answer questions as you read, thanks in advance.

Precision seems to have a winner with the billet wheels.

I have heard the main things that make these wheels better are reduced hub diameter, and lighter weight. is this correct?

It also seems to me that they love high pressure ratios?

Is the there going to be a big advantage at the pressure I plan to run (25-30psi)?

Are there any exhaust housing that are divided available? (Id like to use spool valves)Yes a Non sponsor sells them this way $2500 for two pt6765

My thought here would be pt6765 billet units but I think they would be maxed at about 1400hp what do you think?Seems 1500-1600 would be the max

I know turbonetics has billet wheels on the way any idea how soon?Marchish is what Tnetics said

will they let you stuff them in a TC?
(Id be pissed if I bought a turbos and these cam out right after words, that happened when I bought the 76, a month later the 78 came out)

If its going to be more than say 4 months what do you think about running twin tc76's with 1.0 dived housing and spool valves? FI says this is the best route

I think it would give decent spool plus about a 1:1 back pressure ration up top?

Will the 68mm turbine be enough to really push (high p/r) a 76mm compressor?I Cant find a 3.0l (half a 6.0l ls)car that has pushed a Tnetics 68mm turbine past 20ish psi It seems the smallish turbine flows a lot but has a hard time at higher pressure ratios.

precision runs a 75mm turbine with a 76mm compressor why such a difference?
(Precision = 1.01 ratio Turbonetics= 1.18)

I see turboneticss has new lines coming out, in some ligature it seems that the hurricane is basically a TC and in others it seems that the TN series is similar to a TC, whats going on here, is it basically housing and coating options? (marketing)

I know between the two it a little apples to oranges. I know 76mm units maybe over kill but how bad would the spool up be?

As a point of reference what do you think about gt4094r turbos in comparison? (to any of the scenarios)

I know this is alot of questions thanks again

This is the response I got

Be honest with you....TC76 all the way for the money and power....just add another one. They are awesome units and hard to argue with it. As for the billet....I don't think its worth the time to wait for them.....JMHO


I have a hard time spending money with out a more in depth answer. ( I want to know why) For the record FI was been more than helpful in my past experiences.

Any help First hand or dealer experience would be appreciated
(This car is not being built to any class rules, but will see some street cruising action.)

 

IMO, dont build something around spool valves. Build a turbo kit that will make the power you want and do the necessary things to make it spool fast enough for your liking. This is coming from someone who has used one.

There are so many turbo's out there that people always want to over analyze the decision. There is not a huge different between the PTE76 and the TC76, the tc will spool faster and the PTE will make more power. The Tc's are smaller.

There is hardly ever a perfect turbo that someone is searching for, and if there is there will be another come out next month that might be alittle more perfect.

 

I'm not building around the valve but with them in mind. Either set up would be able to hit the number. The old pte stuff had the same compressor wheels but larger turbines, hence the slower spool and higher power. I'm looking at the Billet stuff (not a whole lot of info out yet but mustang, supra, and evo, guys seem to be picking up power while spooling faster.)

 

What tranny you running?

 

I will run a 4l80

 

I would stick with the TC76s. The Billet wheels will not net you much at 25psi, and you will have no trouble running 8.50s or faster with two. As far as divided housings go they are avail from T-netics. Also they have enough housing sizes to reach a happy medium of response and low back pressure.

One thing to note is anything with a 1:1 pressure ratio generally feels laggy to most, but works best at the track. Most people love driving street setups with a 2:1 pressure ratio because of the way the light up so quick. The 76s will take a bit to come on with 36x cubes but if you are looking to spin it to 7500+ that will be no big deal.

Start with .81s and go from there.

 

The divided housing and the spool valve should allow for higher back pressure when closed and lower back pressure when open ( high boost, high rpm) right?

 

Yes that is what they do, what brand valve are you looking at?

 

I have two t4's from performance metal works

 

Turbonetics has been out of divided housings for 3 months now. Checked yesterday still a no go on the 1.15AR divided

 

I was planning on 1.00 not 1.15. with twins even 1.00 will be large i will check on availability Monday.

 

for what my opinion is worth...
just do what Jose suggests, twin cast wheels will be fine
as for the F1 -68 wheel .... i run 35 + psi thru mine, in the tc 72mm , F1-68 turbine wheel, .81 a/r single entry, and 358 cubes shiftting @ 8200 rpm...methanol fuel
i got no real problems, with the backpressure...
went 6.69 @ 204.98 the other day...
more boost coming

Data that i have logged shows garrett wheels take more p2/p1 ratio to really make it come alive, but make slightly more hp way up high in rpms...
Turbonetics stuff makes more torque down low in rpms...

I have found, running only enough compressor wheel to make the power u want, is way better than oversizing , and having it lazy , ineffecience , and giving turbo engines a bad name ( laggy )

Follow jose's advice....

(just to make it clear , i have not bought turbos off FI ...)
Hurricane = surge slotted TC's
TN = unpolished comp housing , in multiple configurations

 

Crashley,

you suggest getting just enough compressor to get the job done?
I would think 67's would be enough. (they should go 8 flat at my weight.)

I believe FI suggested going 76's because I already have one. (I sold it now)I know they should have plenty in them to go 8.50 (they should be able to go well into the 7's)

I saw you tried 76's on your 358 with .96 A/R hot sides, But you had spool up problems, I also noticed in a later post that the problem may have been ignition related?
Do you think they would have worked fine if the ignition problem was not present?

 

FWIW, I am running twin 6765 billets on my 427 LSX - just made 1160 rwhp at 23psi, but thats through a stick. Haven't turned it up past that point yet.

 

Thanks for the info, (I read the thread that speed inc put up.)your car is making nice power.

 

yes, thats what ive found anyway, compressor wise..
Kenny Dutwhillier ( spelling...) once said to a mate of mine over there, that you only need to run enough turbo , to do the ET you want... any more is a waste....

the 358 cube , 76's and .96 a/rs had a few issues..
most of them solved now..
the .96a/rs where too big, and the converter was too tight, and a bad earth problem.. (with out the earth problem / ignition deal, ...no the converter would been still to tight.)
I also run mechanical injection ( like enderle / hilborn ) , so i got no antilag etc to use....

since then ,same 358 sbc i have twin 72's , with .81 a/r , F1 -68 turbine wheel , but a different converter, which made a world of difference.

the 72 mm wheel is nice deal, it has a BIG p2/p1 ratio map, and when pushed , gets close to the 76mm wheel anyway. Also , its easy to spool too.
I used to have twin 66's on same engine, and i feel the 72's spool just as quick ( or maybe the extra 10 degs timing helps....)

Its probaly not what you want to hear, but i know through my mistakes... choosing parts etc, would be cheaper and the combo would be alot happier ( ie, make more power) , if you bought say package deal like a converter , turbo's , and camshaft of someone like Shawn from VA... ( and no, i have not bought anything off him before, just picking out a smart guy.... )

anyway, food for thought

ash

 

package deal is not my style. plus I don't think Va speed will spec a cam unless they build the engine. I'm no where near them so that's not a very good option. I don't expect everything to work perfectly right of the bat but thats what forums are for. A wealth of knowledge. ( and BS but you have to sift through that and decide what advice you take.) I have had a few turbo cars and helped build a few more, normally I'm good at specing parts but when it comes to my own stuff I over think it, I think

 

That is because we purchased all of them they made.....last one actually goes out today. More in two weeks...

 

LASTLS1 on this forum has already gone 8.0's @17X with his TC76's....more left.

 

What size engine was this with?
will a 36x engine be able to spool these in decent amount of time?